Once integrated circuits of semiconductor chips have been produced on a wafer and the wafer has been separated into individual chips, the chips are usually enclosed in a package, to which they are connected by means of a multiplicity of electrical contacts. The packaged chip is then connected by means of contacts on the package to a larger unit, for example a motherboard, or to a memory module. The semiconductor chip itself has on its upper side, on which the integrated semiconductor circuit is produced, contact areas (pads), which are contacted by the package contacts on the chip, for instance by bonding, soldering or other connecting techniques.
Sometimes semiconductor chips are also electrically connected to other hardware components unpackaged, i.e., without a package being interposed.
In all cases, the semiconductor chip is exclusively contacted from its upper side, i.e., from that side on which the integrated semiconductor circuit is located. This type of contacting follows almost inevitably from the fact that a multiplicity of microscopically small contacts, with dimensions of a few 100 nm or less, have to be positionally adjusted in relation to one another and reliably connected to the package. Since the integrated semiconductor circuit of a semiconductor chip itself has a multiplicity of positionally adjusted and dimensionally optimized switching elements and other structures, the contact pads or contact areas for the contacting through the package are also integrated in the integrated semiconductor circuit. The contact areas are lithographically patterned as a component part of the upper interconnect levels and are produced during the production of the interconnects. A multiplicity of such contact areas distributed over the surface area of the integrated semiconductor circuit can be contacted for instance with the aid of bonding wires or other electrical connecting means.
The not yet laid-open German patent application 103 08 926.8 describes an arrangement of two semiconductor chips which have in their side faces electrical contacts which are to be laterally connected to one another.
In practice the question arises as to how such contacts can be connected by production techniques to form a reliable, durable and positionally adjusted connection of all the electrical lines between the chips. The sawing out of the chips and the pressing of their side faces against one another cannot alone lead to such a connection, if only because the electrical contacts contained in the side faces are flush with the side faces; the electrical contacts, however, must be connected to one another outside the side faces.
Conventional techniques that are used in semiconductor technology are either soldering techniques or bonding techniques, in which additional material is applied to electrical contacts and at the same time heated, in the case of bonding additionally pressed and irradiated with ultrasound.
If bonding or soldering techniques were likewise used for the electrical contacting of lateral contacts produced in chip side faces, pressing of the semiconductor chip in the lateral direction to make the lateral contacts establish contact would at the same time lead to a movement of the mounted semiconductor chip on its carrier, and consequently destroy the semiconductor circuit, or at least damage the contact areas of its metallization level or cause faulty contacts. At the same time, therefore, conventional bonding or soldering techniques cannot necessarily be used for lateral and vertical contacts.
There is no known laid-open method by which such an arrangement of semiconductor chips connected to one another via their side faces can be produced in a simple way and by which the electrical contacts can be connected to one another at the side faces, in order that such an arrangement can be produced reliably, i.e., with an adequately low reject rate, with acceptable technological complexity. In particular, soldering connection techniques are conditional on both semiconductor devices that are to be soldered to one another being in a horizontal position and are therefore not conventionally suitable for producing lateral contacts on chip side faces, especially not at the same time as the contacting of a main chip area.